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CRETACEOUS PLANTS OF AUSTRALIA

The Boola Boola (Rintoul Creek) flora


Specimen by taxa
Taxa recorded
Plant fossils are known from Cretaceous strata at several sites in the Boola Boola Forest near Tyers in Gippsland, Victoria, Australia. The stratigraphy of the Cretaceous rocks in this area has been described in detail by Tosolini et al. (1999) and the fossil floras have been described in a series of papers by Douglas (1963, 1969, 1973), Parris et al. (1995) and McLoughlin et al. (2002). The main fossil assemblages derive from the Locmany Member of the Rintoul Creek Formation, Tyers Subgroup, Strzelecki Group, within the Gippsland Basin. The Boola Boola (Rintoul Creek) fossil assemblages are the representative examples of Douglas´ (1969) ‘Zone B´ flora, which is essentially equivalent to the Phyllopteroides laevis Zone of Cantrill & Webb (1987). These assemblages are of Valanginian to Hauterivian age (ca 140—130 million years old) and include plant macrofossils referable to 33 species of liverworts, isoetaleans, equisetaleans, ferns, seed-ferns, and conifers (podocarps, araucarians and cheirolepids). A single unionid bivalve and two beetle wings were also illustrated from the same deposits by McLoughlin et al. (2002). In addition, acid-digestion of the sediments has revealed rich mesofossil suites of dispersed cuticle fragments, seed coats, seed megaspore membranes, 16 lycophytic megaspore taxa, microspore clusters, fern leptosporangia, charcoalified wood, resin blebs, epiphyllous fungal shields, clitellate annelid cocoons, insect exoskeleton fragments and invertebrate coprolites (McLoughlin et al. 2002, Tosolini et al., 2002). Dettmann (1963) also recovered rich microspore-pollen assemblages from outcrop in this area and these have been the primary basis for dating the Rintoul Creek Formation.
The Boola Boola fossil flora shares some taxa with the well-studied, slightly younger (Aptian), Koonwarra Fossil Bed flora of the Gippsland Basin but lacks several key elements (Ginkgoales, angiosperms and large-leafed araucarian conifers). In this sense, the Boola Boola flora is more similar to Jurassic floras of eastern Australia in its strong representation of bennettitalean, pentoxylalean and other seed-fern remains. The Boola Boola flora differs from northwestern Australian floras of equivalent age by possession of smaller-leafed bennettitaleans, Komlopteris and Pachydermophyllum species and by the lack of dipteridacean and gleicheniacean/lophosoriacean fern macrofossils. This intra-Australian provincialism has been interpreted to be a consequence of palaeolatitude-induced climatic differences. The Boola Boola fossil assemblages were deposited in a range of fluvial facies and probably represent a mix of riparian, upland, and floodbasin mire communities. The floristic diversity, foliar morphologies, strong representation of deciduous taxa and sedimentological data collectively suggest that seasonally cold conditions prevailed during the Valanginian—Aptian in southeastern Australia compared to warmer conditions in the Albian, at which time a range of broad-leafed conifers are represented.
The Swedish Museum of Natural History hosts a substantial collection (481 specimens) of plant fossils from the Boola Boola Forest collected on various expeditions between 1994 and 2008 by S. McLoughlin. The flora is significant in having developed at a relatively high latitude (75-80°S: Veevers et al., 1991), hence it has a role to play in deciphering just how cold (or warm) the polar climates were in the Early Cretaceous. The Boola Boola assemblages also constitute the last expression of the pre-angiosperm floras of southeastern Australia.

References

Cantrill, D. J. and Webb, J. A., 1987. A reappraisal of Phyllopteroides Medwell (Osmundaceae) and its stratigraphic significance in the Lower Cretaceous of eastern Australia. Alcheringa 11, 59-85.

Dettmann, M. E., 1963. Upper Mesozoic microfloras from southeastern Australia. Proceedings of the Royal Society of Victoria 77, 1-148.

Douglas, J. G., 1963. New bennettitalean leaves from the Mesozoic of eastern Australia. Proceedings of the Royal Society of Victoria 77, 197-206.

Douglas, J. G., 1969. The Mesozoic floras of Victoria, parts 1 and 2. Geological Survey of Victoria Memoir 28, 1-310.

Douglas, J. G., 1973. The Mesozoic floras of Victoria, Part 3. Geological Survey of Victoria Memoir 29, 1-185.

McLoughlin, S., Tosolini, A.-M., Nagalingum, N. and Drinnan, A. N. 2002. The Early Cretaceous (Neocomian) flora and fauna of the lower Strzelecki Group, Gippsland Basin, Victoria, Australia. Association of Australasian Palaeontologists Memoirs 26, 1-144.

Parris, K. M., Drinnan, A. N. and Cantrill, D. J., 1995. Palissya cones from the Mesozoic of Australia and New Zealand. Alcheringa 19, 87-111.

Scotese, C. R., 1997. Paleogeographic Atlas. Paleomap progress report 90-0497, 1-45.

Tosolini, A.-M. P., McLoughlin, S., & Drinnan, A. N., 1999. Stratigraphy and sedimentary facies of the Neocomian-Barremian lower Strzelecki Group, Gippsland Basin, Victoria. Australian Journal of Earth Sciences 46, 951-970.

Tosolini, A.-M., McLoughlin, S. & Drinnan, A.N. 2002. Early Cretaceous megaspore assemblages from southeastern Australia. Cretaceous Research 23, 807-844.

Veevers, J. J., Powell, C. McA. and Roots, S. R., 1991. Review of seafloor spreading around Australia. I. Synthesis of the patterns of spreading. Australian Journal of Earth Sciences 38, 373-389.

Senast ändrad 02 May 2017 10:24
Sidansvarig: Anna Lindström, Förste assistent
Anna.Lindstrom@nrm.se

Global palaeogeographic reconstruction for the Early Cretaceous showing the high southern latitude position of the Boola Boola flora. Click for larger image.

Geological map of the west Gippsland area, Victoria, Australia, showing the location of the Boola Boola (Rintoul Creek) plant fossil locality.Click for larger image.

The main Boola Boola fossil locality on Rintoul Creek showing a succession of plant-bearing floodbasin shales, siltstones and fine sandstones. Photo: S. McLoughlin, 2008. Click for larger image.